Writing instrument



FIG. 1 is a left side elevational view of a writing instrument showing my new design in an exploded condition;

FIG. 2 is a rear elevational view, with the cap member in place;

FIG. 3 is a front elevational view of FIG. 2;

FIG. 4 is a left side elevational view of FIG. 2, the right side being a mirror image thereof;

FIG. 5 is a top plan view of FIG. 2; and,

FIG. 6 is a bottom plan view of FIG. 2. 

The ornamental design for a writing instrument, as shown and described. 